1. Field of the Invention
This invention relates to a novel liquid crystal compound and a liquid crystal composition containing the same.
2. Description of the Prior Art
Liquid crystal substances and their compositions have been used in various display devices by utilizing the dielectric anisotropy (abbreviated to .DELTA..epsilon.) and the optical anisotropy (abbreviated to .DELTA.n) of the substances and the compositions, and their display modes are classified into TN type (twisted nematic type), DS type (dynamic scattering type), guest-host type, DAP type, etc. As liquid crystal materials used for these, there is no single compound which can endure various practical uses in the aspect of various characteristics of the display element, i.e., mesomorphic range, driving voltage, response properties, etc.; hence at present, several kinds of liquid crystal compounds or mixtures thereof with non-liquid crystal compounds have been practically used.
In general, a liquid crystal material having an optional .DELTA..epsilon. value can be obtained by adequately blending those having different .DELTA..epsilon. values. In order to obtain a liquid crystal composition having a large .DELTA..epsilon. value, it is necessary to use components having .DELTA..epsilon. values as large as possible, and in this case, those having a good compatibility with other components and making the viscosity of the resulting composition lower are preferred, and the liquid crystal materials are required to be stable to moisture, light, heat, air, etc. At present, however, there is no single compound which satisfies all of such conditions, but several kinds of liquid crystal compounds or blends thereof with compounds similar to liquid crystal compounds have been practically used. Further, particularly recently, liquid crystal display elements which operate within a broad temperature range of low temperatures to high temperatures have come to be required.